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Noncardiovascular Surgery for the Cardiac Patient

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Presentation on theme: "Noncardiovascular Surgery for the Cardiac Patient"— Presentation transcript:

1 Noncardiovascular Surgery for the Cardiac Patient
Anesthesia for Noncardiac Surgery 4/6/2017 Noncardiovascular Surgery for the Cardiac Patient Wayne E. Ellis, Ph.D., CRNA Wayne E. Ellis

2

3 Statistics 30 million noncardiac surgeries annually
3 million individuals with known or probable Coronary Artery Disease 50,000 (1.7%) Perioperative MI’s annually 10, ,000 deaths per year ( % mortality) % of all perioperative deaths annually Costs > $ 500 million per year 4/6/2017 WE Ellis

4 Preoperative Assessment
Ischemia and Heart Disease 4/6/2017 Preoperative Assessment History Physical exam Laboratory findings and other tests 4/6/2017 WE Ellis WE Ellis

5 Ischemia and Heart Disease
4/6/2017 History - Do a good one!!! Stability of angina NYHA Class I: Mild angina without impairment Class IV: Angina at rest Exercise tolerance! Ventricular function Associated cardiovascular diseases Medication 4/6/2017 WE Ellis WE Ellis

6 Recent Myocardial Infarction
Anesthesia for Noncardiac Surgery 4/6/2017 Recent Myocardial Infarction Less than three months Patient < 70 years of age Location of surgery Duration of surgery Poor LV function CHF Enlarged heart Arrhythmias Increased risk of morbidity and MORTALITY 4/6/2017 WE Ellis Wayne E. Ellis

7 Perioperative Predictors
Recent MI < 6 months Current CHF Only consistent predictors of perioperative outcome 4/6/2017 WE Ellis

8 Anesthesia for Noncardiac Surgery
4/6/2017 Prior MI % of patients having a reinfarction compared to the time from MI to operation Tarhan et al, 1972 3 mon: 37% 3-6 mon: 16% >6 mon: 5.6% Risk factors for reinfarction Wayne E. Ellis

9 Anesthesia for Noncardiac Surgery
4/6/2017 Prior MI % of patients having a reinfarction compared to the time from MI to operation Steen et al, 1978 3 mon: 27% 3-6 mon: 11% >6 mon: 6% Risk factors for reinfarction Wayne E. Ellis

10 Anesthesia for Noncardiac Surgery
4/6/2017 Prior MI % of patients having a reinfarction compared to the time from MI to operation Rao et al, 1978 3 mon: 5.7% 3-6 mon: 2.3% >6 mon: 1.5% Risk factors for reinfarction Wayne E. Ellis

11 Anesthesia for Noncardiac Surgery
4/6/2017 Prior MI % of patients having a reinfarction compared to the time from MI to operation Shah et al, 1990 3 mon: 4.3% 3-6 mon: 4.3% >6 mon: 5.7% Age undeterminate: 3.3% Risk factors for reinfarction Wayne E. Ellis

12 Anesthesia for Noncardiac Surgery
4/6/2017 Prior MI Mortality due to reinfarction: about 30% Historically cited as 50% Risk factors for reinfarction Wayne E. Ellis

13 Anesthesia for Noncardiac Surgery
4/6/2017 Prior MI The differences between the studies Monitoring ICU stay Can apply these interventions to all of your patients? $$$$$$$ Wayne E. Ellis

14 Challenge of anesthesia
Anesthesia for Noncardiac Surgery 4/6/2017 Challenge of anesthesia Adequately evaluate the patient Provide adequate anesthesia Prevent myocardial injury Maximize postoperative pain management 4/6/2017 WE Ellis Wayne E. Ellis

15 RISK FACTORS genetic predisposition age gender obesity hyperlipedemia
diabetes mellitus hypertension stress, tobacco, and smoking 4/6/2017

16 Smoking Increases the risk of an initial cardiac event and doubles the rate of subsequent infarction and death. Risk rapidly declines after stopping and by 3 years reaches that of survivors who have never smoked. 4/6/2017

17 Assessment of risk factors
Anesthesia for Noncardiac Surgery 4/6/2017 Assessment of risk factors Cigarette smoking Hypertension Diabetes Family history May have a normal physical 4/6/2017 WE Ellis Wayne E. Ellis

18 Perioperative estimation of cardiac risk
Recent preoperative MI average 8% reinfarction if within 3 months Optimal preparation Invasive Monitoring Without monitoring > 30% Age > 70 10 fold increased risk 4/6/2017 WE Ellis

19 Coronary Artery Disease
* 07/16/96 Coronary Artery Disease Most common cause of premature death for males between 35-45years of age. Each year 1.5 million MI’s occur in the U.S. 280,000 OHS every year in the U.S. $60 billion spent annually to treat CAD OHS represents 80% of the total adult operations performed at most medical centers in the U.S. 4/6/2017 *

20 Atheroscelerosis begins as crystals of cholesterol adheres to the intima. These crystals then form a larger matrix that stimulates surrounding fibrous and smooth muscle tissue growth to create additional layers i.e.) larger plaques can grow 4/6/2017

21 Atheroscelerosis Larger plaques then develop into total obstructive lesions, resulting in sclerosis(fibrosis) Atherosclerosis lesions become symptomatic with 75% stenosis of one or more coronary vessels = ischemia, which depresses the myocardial function, causes chest pain (angina pectoris). 4/6/2017

22 CAD Modulated by 3 factors 1) Myocardial oxygen demand
2) Myocardial oxygen supply 3) Coronary blood flow 4/6/2017

23 Myocardial Oxygen Demand (MvO2)
Heart extracts more 02 than any other organ, 50-70% at rest BP and HR provides a basic guideline for Mv02 contractility and myocardial wall tension are primary determinants of Mv02 wall tension can be lowered by decreasing preload contractility can be lowered by beta blockers or pain management relief 4/6/2017

24 Determinants of Oxygen Supply
Anesthesia for Noncardiac Surgery 4/6/2017 Determinants of Oxygen Supply Degree of muscular contractility Frank Startling Principle The more stretch placed on a muscle fiber before contraction, the more forceful the contraction. Ventricular preload 4/6/2017 WE Ellis Wayne E. Ellis

25 Wall tension of the left ventricle
Anesthesia for Noncardiac Surgery 4/6/2017 Wall tension of the left ventricle Afterload With increased resistance Hypertrophy Increased muscle mass Maintain normal wall tension 4/6/2017 WE Ellis Wayne E. Ellis

26 Anesthesia for Noncardiac Surgery
4/6/2017 Heart rate The faster the rate the more oxygen required The faster the rate there is less time for tissue oxygenation 4/6/2017 WE Ellis Wayne E. Ellis

27 Myocardial Oxygen Supply
Any increase in myocardial oxygen requirements can be met only by raising coronary blood flow Maintaing the bloods oxygen carrying capacity is the secondary objective for cardiovascular perfusion 4/6/2017

28 Myocardial Oxygen Supply
Oxygen content = Ca02 CaO2 = (hgb x 1.34) x Sa02 + (Pa02 x ) 1.34 = milliliters of 02 per gm of hgb Sa02 = % of oxyhemoglobin of total hemoglobin(fractional saturation) 0.003 = oxygen solubility in plasma 4/6/2017

29 Influences affecting oxygen supply
Anesthesia for Noncardiac Surgery 4/6/2017 Influences affecting oxygen supply Coronary blood flow Left ventricle during diastole With increased heart rate diastole is shortened Coronary perfusion pressure Diastolic pressure minus left ventricular end diastolic pressure CPP = DP-LVEDP 4/6/2017 WE Ellis Wayne E. Ellis

30 Anesthesia for Noncardiac Surgery
4/6/2017 Oxygen Supply With coronary stenosis Improve CPP Increase systemic pressure Lower elevated LVEDP Nitroglycerin Hgb Level Oxygen saturation 4/6/2017 WE Ellis Wayne E. Ellis

31 Myocardial Oxygen Supply
Any increase in myocardial oxygen requirements can be met only by raising coronary blood flow Maintaing the bloods oxygen carrying capacity is the secondary objective for cardiovascular perfusion 4/6/2017

32 Coronary blood flow Perfusion of the left ventricle takes place almost entirely during diastole, whereas the right ventricle occurs mostly with systole. Not only is diastole important, but the length of diastole is critical in determining the volume of left ventricular subendocardial flow 4/6/2017

33 Coronary blood flow Coronary perfusion psi = aortic diastolic pressure(AoDp) - LVEDP Note hypotension is more likely to produce ischemia than hypertension 4/6/2017

34 Anesthesia for Noncardiac Surgery
4/6/2017 Temperature Keep warm Decreasing temperature Shift Oxygen dissociation curve to left Hgb retains oxygen at tissue level Prevent alkalosis 4/6/2017 WE Ellis Wayne E. Ellis

35 Anesthesia for Noncardiac Surgery
4/6/2017 Evaluation Select patients at highest risk of difficulty Reinfarction in 1st 6 months post MI high High fatality rate CABG or Angioplasty first Choice of monitoring 4/6/2017 WE Ellis Wayne E. Ellis

36 Physical exam: Not a lot here
Ischemia and Heart Disease 4/6/2017 Physical exam: Not a lot here Vital signs Cardiac exam PMI Gallops S4: HTN, S3: increased LVEDP Apical systolic murmur Papillary muscle dysfunction Precordial bulge Other signs of LV function JVD, pulmonary signs 4/6/2017 WE Ellis WE Ellis

37 Physical Examination Cardiovascular JVD Carotid Bruits Murmurs
S3, S4, Click, Rub Pitting Edema Pulses Vascular Access 4/6/2017 WE Ellis

38 Physical Examination Pulmonary Wheezes Rales Rhonchi A-P Diameter
4/6/2017 WE Ellis

39 Diagnostic Studies ECG CXR ischemia infarction dysrhythmias
heart block conduction abnormalities CXR cardiomegaly pulmonary vascular congestion pulmonary edema pleural effusion 4/6/2017 WE Ellis

40 ECG How many msec after the J point?? How many mm??
* 07/16/96 ECG How many msec after the J point?? How many mm?? A resting 12 lead is not a whole lot of good for detecting ischemia 4/6/2017 *

41 Chest X-Ray Edema, effusions Calcification of vessels, valves
* 07/16/96 Chest X-Ray Cardiomegaly Signs of ventricular dysfunction Edema, effusions Complicating diseases Calcification of vessels, valves Pulmonary disease 4/6/2017 *

42 Blood tests CK, other cardiac enzymes Associated diseases
* 07/16/96 Blood tests CK, other cardiac enzymes R/O after surgery: Usually an MB of about 5-7% of total CK Triponin >7 positive Associated diseases Diabetes, thyroid disease 4/6/2017 *

43 Diagnostic Studies Cardiac Catheterization Two types of information
Hemodynamic parameters Visualization of vessels, wall motion 4/6/2017 WE Ellis

44 Primary Treatment Antiplatelet agents(abciximab,eptifibatide, tirofiban, integullin) GPIIb-IIIa antagonists inhibit platelet function by blocking the GPIIb-IIIa receptor, the final pathway of platelet aggregation thereby decreasing thrombi development and prevents arterial vessel occlusion 4/6/2017

45 Percutaneous Coronary Intervention
Advantages include: higher recanulazation rates improved blood flow through the infarct-related vessel improved LV function lower in-hospital mortality rates 4/6/2017

46 Normal Hemodynamic Measurements
RA (mean) RV (mean) PA (sys/dys) LA or wedge (mean) LV (sys/dys) Systemic arterial (sys/dys) 2 - 8 /2 - 8 /4 - 12 2 - 10 /3 - 12 / 4/6/2017 WE Ellis

47 Monitoring Routine Pulse Oximetry PNS Capnography Temperature ECG
Core and peripheral ECG Leads V5 and II 4/6/2017 WE Ellis

48 Monitors of Cardiac Performance
Arterial Line Standard of Care Site selection Pulmonary Artery Catheter Provides means for assessing filling pressures Reliable site for drug administration Transesophageal Echocardiography 4/6/2017 WE Ellis

49 Evaluation of the heart
Anesthesia for Noncardiac Surgery 4/6/2017 Evaluation of the heart The pump Ventricular function The fuel supply Degree of coronary artery disease 4/6/2017 WE Ellis Wayne E. Ellis

50 Anesthesia for Noncardiac Surgery
4/6/2017 Ventricular Function History Periods of CHF Diuretics Sleep patterns Sleeping position Wakes up at night Night sweats Chest pain at rest 4/6/2017 WE Ellis Wayne E. Ellis

51 Anesthesia for Noncardiac Surgery
4/6/2017 Physical signs Jugular distention Chest sounds Rales Extra heart sounds 4/6/2017 WE Ellis Wayne E. Ellis

52 Echocardiography Assess ejection fraction Wall motion abnormalities
Valvular function 4/6/2017 WE Ellis

53 MUGA Multiple uptake Gated Acquisition Scan
Accurate estimate of ejection fraction 4/6/2017 WE Ellis

54 Anesthesia for Noncardiac Surgery
4/6/2017 EKG Is it necessary for evaluation? Compare to previous EKG If none present Establish base line May be normal 4/6/2017 WE Ellis Wayne E. Ellis

55 Exercise Tolerance Test
Anesthesia for Noncardiac Surgery 4/6/2017 Exercise Tolerance Test Inadequate exercise is non-diagnostic test Not a negative test Unable to exercise Thallium Scan Thallium - Persantine Scan Dobutamine assisted scan 4/6/2017 WE Ellis Wayne E. Ellis

56 Cardiac Catheterization
Anesthesia for Noncardiac Surgery 4/6/2017 Cardiac Catheterization Gold standard Determine degree of large vessel disease Not predictor of small vessel disease Done prior to CABG or Angioplasty Not necessary before routine surgery?? 4/6/2017 WE Ellis Wayne E. Ellis

57 Patients requiring CABG or Angioplasty
Anesthesia for Noncardiac Surgery 4/6/2017 Patients requiring CABG or Angioplasty Stenosis of LAD < 50% Severe three vessel dysfunction Severe two vessel disease with poor LV function 4/6/2017 WE Ellis Wayne E. Ellis

58 Preoperative Evaluation
Anesthesia for Noncardiac Surgery 4/6/2017 Preoperative Evaluation History Physical assessment EKG evaluation Exercise tolerance Chest X-ray Lab studies 4/6/2017 WE Ellis Wayne E. Ellis

59 Preoperative Evaluation
Current Medication Beta-blockers Calcium Channel Blockers Antidysrhythmia agents Nitrates Diuretics Antihypertensive agents 4/6/2017 WE Ellis

60 Anesthesia for Noncardiac Surgery
4/6/2017 Dyspnea Activity Rest What starts it How long lasts 4/6/2017 WE Ellis Wayne E. Ellis

61 Perioperative Predictors
Angina Associated with angiographically significant CAD > 70% stenosis At Risk for significant CAD 90% of males > 40 90% of females > 60 Stable angina “Conspicuously insignificant predictor” (Goldman) 4/6/2017 WE Ellis

62 History of anginal pattern
Anesthesia for Noncardiac Surgery 4/6/2017 History of anginal pattern Stable No recent change Medications Exercise tolerance Frequency Require little to no additional work-up 4/6/2017 WE Ellis Wayne E. Ellis

63 History of Anginal Pattern
Unstable Change in occurrence or type of pain Requires further evaluation Myocardial Infarction When 4/6/2017 WE Ellis

64 Perioperative Predictors
Congestive Heart Failure LV Failure Poor prognosis Patient with CAD One of most important predictors of short and long term cardiac mortality Signs with predictive value Third heart sound Jugular venous distention 4/6/2017 WE Ellis

65 Perioperative Predictors
Preoperative Ejection Fraction < 40% Predictive of Perioperative MI Reinfarction Perioperative ventricular dysfunction Ejection Fraction < 30% 1 year cumulative mortality > 30% 4/6/2017 WE Ellis

66 Perioperative Predictors
Hypertension Risk Factor for: Ischemic heart disease CHF Stroke Ability to predict is controversial Diastolic pressure > 110 significant cardiac risk 4/6/2017 WE Ellis

67 Perioperative Predictors
Diabetes Mellitus Increased risk for CAD Cardiomyopathy Abnormal autonomic function/tone 20-40 % of diabetics Increased intraoperative risk of Ischemia Infarction 4/6/2017 WE Ellis

68 Perioperative Predictors
Dysrhythmias Frequent PVCs or PACs Independent predictor Intraoperative difficulty PVCs most frequent indicator of postoperative morbidity & mortality 4/6/2017 WE Ellis

69 Perioperative Predictors
Peripheral Vascular Disease High risk of Perioperative Cardiac Mortality Vascular Surgery > 15% risk of MI Non-vascular surgery unknown 4/6/2017 WE Ellis

70 Perioperative Predictors
Valvular Heart Disease Aortic Stenosis Increased perioperative mortality Underlying heart failure Difficulties in perioperative fluid management Other valvular disorders Predictors uncertain 4/6/2017 WE Ellis

71 Perioperative Predictors
Cholesterol Risk unknown Smoking Not a predictor of adverse cardiac outcomes Previous CABG Protection against development of perioperative cardiac morbidity Previous angioplasty No accurate data 4/6/2017 WE Ellis

72 Perioperative Predictors
Cardiovascular Therapy Beneficial effects Nitrates Beta Blocking Agents Calcium entry blocking agents Preoperative withdrawal yields higher incidence of perioperative ischemia, dysrhythmia, MI and cardiac death Intraoperative prophylaxis - Undetermined 4/6/2017 WE Ellis

73 Dynamic Predictors Acute imbalances in myocardial oxygen supply and demand may produce ischemia that may result in irreversible cardiac morbidity Hypertension Hypotension Tachycardia 4/6/2017 WE Ellis

74 Dynamic Predictors Hypertension No conclusive correlation
Intraoperative Hypertension MI Acute Hypertension Precedes intraoperative ischemic events 50% of time 4/6/2017 WE Ellis

75 Dynamic Predictors Hypotension
25 % of ischemic events associated with > 20 % decrease in systolic blood pressure 6 % decrease in MAP Important predictor of PCM Higher reinfarction rate 15.2 % vs. 3.2 % Intraoperative hypotension > 30% decrease in systolic BP > 10 minutes duration 4/6/2017 WE Ellis

76 Dynamic Predictors Tachycardia Myocardial Ischemia TEE
Combination with hypotension Ominous Significant indicator of PCM Myocardial Ischemia ST changes Not a clear indicator of PCM TEE Most sensitive, earlier indices of ischemia Before ST segment changes 4/6/2017 WE Ellis

77 Treatment of ischemia Improves systolic run off
* 07/16/96 Treatment of ischemia Is it real? Optimize oxygenation and hemodynamics IV NTG SL Nifedipine Diltiazem Intra-aortic Ballon Pump Improves systolic run off Provides diastolic augmentation 4/6/2017 *

78 Anesthesia for Noncardiac Surgery
4/6/2017 Anesthesia Goals Balance supply and demand Control heart rate Normal to slow range Maintain CPP Prevent hypotension Prevent increased LVEDP Optimize arterial oxygen and carbon dioxide status Keep patient normothermic Higher threshold for transfusion 4/6/2017 WE Ellis Wayne E. Ellis

79 Anesthesia Goal Does technique make a difference? Laryngoscopy
* 07/16/96 Anesthesia Goal Does technique make a difference? Laryngoscopy Maintenance Regional anesthesia 4/6/2017 *

80 Preoperative Preparation
Angina Medications to control it Blood pressure controlled Diastolic < 95 torr Congestive heart failure treated Diuretics Afterload reduction Bedrest if indicated Control diabetes

81 Preoperative Medications
Sedation Prevent tachycardia Hypertension Prepared for hypoxia Supplemental oxygen Calcium channel blockers not protective of perioperative ischemia Antihypertensives continue on day of surgery Stop Diuretics

82 Antianginal medications
Beta-blockers Calcium Channel Blockers Nitrates Nitropaste morning of surgery 4/6/2017 WE Ellis

83 Beta Blockers Negative inotropic effects
Withdrawal following stoppage of beta blocker Unstable angina Myocardial infarction

84 Monitoring EKG Blood Pressure Temperature Pulse oximetry End tidal CO2

85 Arterial Catheter Beat to beat blood pressure monitoring ABGs
Early detection of hypotension

86 Laboratory studies HGB & HCT Electrolytes Liver function studies
Creatine clearance Osmolality

87 Noninvasive beat to beat analysis
Finapress Ohmeda

88 PA catheter Assessment of LV Function Early detection of ischemia
“v” waves Increased PCWP More accuracy than CVP Intravascular volume problems Especially in patients with severe lung disease

89 Transesophageal Echocardiography
Demonstrates regional wall motion abnormalities Suggestive of ischemia Most accurate measure of left ventricular volume

90 Non-invasive Continuous Cardiac Output Monitors
Transesophageal Doppler Thoracic impedance Limited Accuracy is controversial No information about systemic vascular resistance Measure CVP

91 Improved outcomes Aggressive monitoring & treatment Vasoactive drugs
Reduced intraoperative ischemia MI < 6 months has better survival rate Occurrence reduced from 30-5% Multi-institution study over last 10 years 5000 patients Continued for 3 days post-operatively

92 Decision to use Invasive Monitoring
Patients with severe inoperable CAD Chronic stable angina undergoing significant abdominal or thoracic surgery Large blood loss History of remote MI with stable angina Not necessary to use invasive monitors

93 Anesthetic Management
Regional vs general Anesthetic management skills more important than technique Safest technique is the one the practitioner does best

94 General anesthesia Avoids sympathectomy Risks with intubation
Sympathetic stimulation Hypoxia Increased catecholamines Loss of subjective monitor Chest pain Ischemia

95 General Anesthesia required
Narcotics Effective control of catecholamines Respiratory depression Prolonged ventilation

96 Avoid Ketamine Hypertension Tachycardia Use in trauma

97 Etomidate Painful to inject More CV stability

98 Barbiturate Direct depressant Extended duration of activity
Smaller doses 1-2 mg/kg Add benzodiazepines and narcotic

99 Benzodiazepines Quell anxiety Hemodynamic stability
Extended duration of action Potential for hypoxia Lidocaine Esmolol

100 Muscle Relaxants Avoid pancuronium Doxacurium Tachycardia
ST segment changes consistent with ischemia Doxacurium Duration similar to pancuronium No cardiovascular effects

101 Avoid Histamine releasing drugs
Curare Atracurium Mivacurium <15 mcg/kg Hypotension Tachycardia

102 Inhalation Agents Potential for coronary steal
Alters coronary autoregulation Alters regional blood flow Little influence on outcome

103 Nitrous Oxide Constricts coronary arteries
Aggravates myocardial ischemia High FiO2 recommended Maintain saturation at %

104 Regional Anesthesia Monitor patient more accurately
Control sympathetic responses Fluids Esmolol

105 Intraoperative predictors
Choice of anesthetic Site of surgery Duration of Anesthesia Emergency Surgery

106 Intraoperative predictors
Choice of Anesthetic No difference in infarction rate GETA vs. Regional No significant hypotension No significant tachycardia TURP Regional decreased risk post MI Reinfarction rate SAB < 1% GETA 2-8%

107 Intraoperative predictors
Choice of Anesthetic Patient with CHF will benefit from regional technique Sympathectomy Decreased preload Coronary Steal Potent inhalation agents vs. narcotics

108 Intraoperative predictors
Site of Surgery Thoracic and upper abdominal 2-3 X’s risk of extremity procedures Duration of Anesthetic > 3 hours > risk of morbidity & mortality Emergency Surgery 2 - 5 X’s greater risk than nonemergent surgery

109 Cardioactive drugs Nitroglycerin Lower LVEDP Vasodilator
Poor ventricular function

110 Esmolol Control heart rate and blood pressure Induction Emergence

111 Labetalol Mixed alpha and beta Control hypertension
Heart rate management

112 Lidocaine Blunt effects of intubation
1.5 mg/kg 4-6 minutes prior to intubation

113 Clonidine Less hypertension Decreased anesthesia requirements

114 Nifedipine Controlling hypertension Manage coronary artery spasm

115 Postoperative Management
Maintain analgesia Balance supply and demand Supplemental oxygen Continue monitoring into postoperative period Early transfusion

116 Coronary Artery Disease
Major Goal Balance Supply and Demand Primary Determinants of Myocardial Oxygen Demand Wall tension and Contractility

117 Coronary Artery Disease
Factors modifying coronary blood flow diastolic time perfusion pressure coronary vascular tone intraluminal obstruction

118 Coronary Artery Disease
Myocardial O2 Extraction infrequently the cause of ischemia intraoperatively Arterial O2 Content Correction of anemia High FiO2

119 Hemodynamic Goals for the Patient with CAD
P - keep the heart small, decrease wall tension, increase perfusion pressure A - maintain, hypertension better than hypotension C - depression is beneficial when LV function is adequate R - slow, slow, slow

120 Hemodynamic Goals for the patient with CAD
Rhythm - usually sinus MVO2 - control of demand frequently not enough, monitor for and treat “supply ischemia CPB - elevated ventricular filling pressure usually not needed after CABG

121 Anesthetic Technique Goals of Anesthesia loss of conciousness amnesia
analgesia suppression of reflexes (endocrine and autonomic) muscle relaxation

122 Inhalation Agents Advantages
Myocardial oxygen balance altered favorably by reductions in contractility and afterload Easily titratable Can be administered via CPB machine Rapidly eliminated

123 Inhalation Agents Disadvantages Significant hemodynamic variability
May cause tachycardia or alter sinus node function Possibility of “coronary steal syndrome”

124 Coronary Steal Arteriolar dilation of normal vessels diverts blood away from stenotic areas Commonly associated with adenosine, dipyridamole, and SNP Forane causes steal and new ST-T segment depression May not be important since Forane reduces SVR, depresses the myocardium yet maintains CO

125 Opioids Advantages Excellent analgesia Hemodynamic stability
Blunt reflexes Can use 100% oxygen

126 Opioids Disadvantages
May not block hemodynamic and hormonal responses in patients with good LV function Do not ensure amnesia Chest wall rigidity Respiratory depression

127 Induction Drugs Barbiturates Benzodiazepines Ketamine Etomidate

128 Nitrous Oxide Rarely used due to: increased PVR
depression of myocardial contractility mild increase in SVR air expansion

129 Muscle Relaxants Used to: facilitate intubation prevent shivering
attenuate skeletal muscle contraction during defibrillation

130 Postoperative predictors
Ischemia does occur most commonly in the postoperative period Persists for 48 hours or longer following non-cardiac surgery Predictor value is unknown Goldman, L., (1983) Cardiac Risk and Complications of noncardiac surgery, Annals of Internal Medicine. 98:

131 4/6/2017 WE Ellis


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